Relaxin fusion polypeptides and uses thereof

ABSTRACT

The present invention relates to Relaxin fusion polypeptides, in particular to Relaxin 2 fusion polypeptides and uses thereof. Thus, the invention provides Relaxin fusion polypeptides, nucleic acid molecules, vectors, host cells, pharmaceutical compositions and kits comprising the same and uses of the same including methods of treatment. The polypeptides and compositions of the invention may be useful, in particular, in the treatment of cardiovascular diseases, for example for the treatment of heart failure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser. No. 16/480,568, filed on Jul. 24, 2019, which application is a U.S. National Stage application of International Application No. PCT/EP2018/051757, filed on Jan. 24, 2018. International Application No. PCT/EP2018/051757 claims benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 62/450,338, filed Jan. 25, 2017. Each of the above listed applications is incorporated by reference herein in its entirety for all purposes.

REFERENCE TO THE SEQUENCE LISTING

This application incorporates by reference a Sequence Listing filed together with this application in computer readable form (CRF) as a text file entitled “RLX2-100-SequenceListing” created on Nov. 17, 2021 and having a size of 99,343 bytes.

FIELD OF THE INVENTION

The present invention relates to Relaxin fusion polypeptides. In particular, the present invention relates to Relaxin 2 fusion polypeptides and uses thereof.

BACKGROUND

Relaxin is a peptide hormone that belongs to the insulin superfamily. In humans, the Relaxin peptide family includes seven peptides of high structural but low sequence similarity: Relaxin 1, 2 and 3, and the insulin-like peptides INSL3, INSL4, INSL5 and INSL6. The coding region of the relaxin genes starts with the signal peptide followed by a B polypeptide chain, C peptide and an A polypeptide chain. The signal peptide and the C peptide are proteolytically removed to produce the mature Relaxin protein, which consists of the A and B chains covalently linked by two inter-chain disulphide bonds. The A chain has an additional intra-chain disulphide bond. The mature Relaxin protein has a molecular weight of approximately 6000 Da.

Relaxin is a pleiotropic hormone that is known to mediate systemic haemodynamic and renal adaptive changes during pregnancy. Relaxin has also been shown to have anti-fibrotic properties and to have beneficial effects in heart failure. Heart failure is associated with significant morbidity and mortality. It is characterized by complex tissue remodelling involving increased cardiomyocyte death and interstitial fibrosis (Bathgate et al., 2013; Felker et al., 2014; Mentz et al., 2013; Tietjens et al., 2016; Wilson et al., 2015). Relaxin activates a number of signalling cascades which have been shown to be beneficial in the setting of ischemia-reperfusion and heart failure (Bathgate et al., 2013). These signalling pathways include activation of the phosphoinositide 3-kinase pathway and activation of the nitric oxide signalling pathway (Bathgate et al., 2013).

Clinical trials have been conducted using unmodified recombinant human Relaxin 2, serelaxin. Serelaxin is currently in a phase III clinical trial for acute decompensated heart failure (ADHF). In this study, serelaxin was dosed by continuous intravenous infusion for 48 hours to hospitalized heart failure patients (ClinicalTrials.gov Identifier: NCT02064868). In previous completed clinical trials, intravenous administration of serelaxin improved the markers of cardiac, renal and hepatic damage and congestion (Felker et al., 2014; Teerlink et al., 2013; Metra et al., 2013). However, due to the rapid clearance of serelaxin from the patients' circulation, the therapeutic effect was limited to hospitalized patients and the positive effects rapidly disappeared once intravenous injection stopped. Additionally, approximately one third of the patients experienced a significant blood pressure drop (>40 mm Hg) after receiving serelaxin intravenously, with the consequence that the dose had to be reduced by half or even more.

WO 2013/004607 describes recombinant single chain Relaxin fusion polypeptides in which a Relaxin A chain polypeptide is fused to a Relaxin B chain polypeptide with a linker sequence. The authors found that a linker length of at least five amino acids and less than fifteen amino acids was required for Relaxin activity. WO 2013/004607 also describes recombinant single chain Relaxin 2 fusion polypeptides fused to the Fc domain of antibodies, which exhibited an improved half-life over wild-type Relaxin 2.

Given the promising clinical studies conducted so far with unmodified recombinant Relaxin, there remains a need for further recombinant Relaxin fusion polypeptides which retain a Relaxin biological activity and provide advantages such as an extended half-life and convenient dosing.

SUMMARY OF INVENTION

The present invention is concerned with Relaxin fusion polypeptides comprising a Relaxin A chain and a Relaxin B chain linked by a Linker polypeptide, in which the Linker polypeptide comprises at least 15 amino acids. In connection therewith, the invention provides a fusion polypeptide, a nucleic acid molecule, a vector, a host cell, a pharmaceutical composition and a kit comprising the same and uses of the same including methods of treatment.

Aspects and embodiments of the invention are set out in the appended claims. These and other aspects and embodiments of the invention are also described herein.

BRIEF DESCRIPTION OF FIGURES AND SEQUENCE LISTING

The present invention will now be described in more detail with reference to the attached Figures, in which:

FIG. 1 provides a schematic representation and abbreviated names of Relaxin 2 fusion polypeptides according to some embodiments of the invention;

FIG. 2 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (Fc_hRLX2_4-15AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively);

FIG. 3 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (Fc-TM_hRLX2_4-15AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively; underlined and bold are the TM mutations in the Fc part);

FIG. 4 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (Fc-FQQ_hRLX2_4-15AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively; underlined and bold are the FQQ mutations in the Fc part);

FIG. 5 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (Fc-YTE_hRLX2_4-15AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively; underlined and bold are the YTE mutations in the Fc part);

FIG. 6 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (Fc-YTE-TM_hRLX2_4-15AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively; underlined and bold are the YTE-TM mutations in the Fc part);

FIG. 7 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (Fc-YTE-FQQ_hRLX2_4-15AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively; underlined and bold are the YTE-FQQ mutations in the Fc part);

FIG. 8 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (Fc-G4P_hRLX2_4-15AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively);

FIG. 9 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (Fc_hRLX2_15-15AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively);

FIG. 10 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (Fc-TM_hRLX2_15-15AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively; underlined and bold are the TM mutations in the Fc part);

FIG. 11 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (Fc-FQQ_hRLX2_15-15AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively; underlined and bold are the FQQ mutations in the Fc part);

FIG. 12 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (Fc-YTE_hRLX2_15-15AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively; underlined and bold are the YTE mutations in the Fc part);

FIG. 13 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (Fc-YTE-TM_hRLX2_15-15AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively; underlined and bold are the YTE-TM mutations in the Fc part);

FIG. 14 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (Fc-YTE-FQQ_hRLX2_15-15AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively; underlined and bold are the YTE-FQQ mutations in the Fc part);

FIG. 15 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (Fc-G4P_hRLX2_15-15AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively);

FIG. 16 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (Fc-TMΔTHTΔK_hRLX2_21-15AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively); underlined and bold are the TMΔTHTΔK mutations in the Fc part);

FIG. 17 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (Fc-TMΔTHTΔK_hRLX2(BA)_21-15AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively); underlined and bold are the TMΔTHTΔK mutations in the Fc part);

FIG. 18 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (hRLX2_Fc-TMΔTHTΔK_15-24AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively); underlined and bold are the TMΔTHTΔK mutations in the Fc part);

FIG. 19 shows the nucleotide (top) and amino acid (bottom) sequences of a Relaxin 2 fusion polypeptide according to an embodiment of the invention (hRLX2(BA)_Fc-TMΔTHTΔK_15-24AA) (underlined are the Connector (single underlining) and the Linker (double underlining) sequences, respectively); underlined and bold are the TMΔTHTΔK mutations in the Fc part);

FIG. 20 shows the in vitro activity of some Relaxin 2 fusion polypeptides of the invention in RXFP1-expressing cells. Relative light units (RLU) represents the stimulation of cAMP production;

FIG. 21 shows the in vitro activity (stimulation of cAMP production) of some Relaxin 2 fusion polypeptides of the invention in RXFP1-expressing cells;

FIG. 22 shows the specificity of some Relaxin 2 fusion polypeptides of the invention for the relaxin-2 receptor;

FIG. 23 shows induction of VEGF expression by some Relaxin 2 fusion polypeptides of the invention. In this figure, “zero=1” means that the activity measured with a mock “no treatment” control (i.e. without addition of RLX2 or RLX2 fusion polypeptides in the assay) was taken as the baseline (i.e. the fold change value of “no treatment” control is 1);

FIG. 24 shows rat PK profiles of the fusion polypeptide Fc_hRLX2_4-15AA (4 mg/kg) administered intravenously (top) or subcutaneously (bottom);

FIG. 25 shows rat PK profiles of the fusion polypeptide Fc_hRLX2_15-15AA (4 mg/kg) administered intravenously (top) or subcutaneously (bottom);

FIG. 26 shows mouse PK profiles of the fusion polypeptide Fc_hRLX2_15-15AA (6 mg/kg) administered intravenously (“IV”, circles) or subcutaneously (“SC”, triangles). “CL” represents total body clearance of Fc-Relaxin following IV administration and “CL/F” represents the apparent total body clearance of Fc-Relaxin following SC administration;

FIG. 27 shows mouse PK profiles of the fusion polypeptide Fc_hRLX2_15-15AA (1 mg/kg (circles), 6 mg/kg (squares) and 30 mg/kg (triangles)) administered subcutaneously. “CL” represents total body clearance of Fc-Relaxin following IV administration and “CL/F” represents the apparent total body clearance of Fc-Relaxin following SC administration;

FIG. 28 shows the in vitro activity of some Fc-Relaxin-2 fusion polypeptides of the invention in human (A) and mouse (B) cell lines and RXFP2 selectivity (C), in cell-based cAMP assays;

FIG. 29 shows prevention of isoproterenol-induced cardiac hypertrophy in mice treated with Fc_hRLX2_15-15AA. (A) represents the ratio of Heart Weight (HVV)/Tibia Length (TL) (mg/mm), (B) represents the Collagen content (μg/mg tissue), for the 6 groups tested: (1) vehicle, (2) Fc_hRLX2_15-15AA, (3) isoproterenol, (4) isoproterenol+enalapril, (5) isoproterenol+rhRLX2, (6) isoproterenol+Fc_hRLX2_15-15AA.

Key to SEQ ID NOs: Construct Type SEQ ID NO. Fc_hRLX2_4-15AA DNA 1 Fc_hRLX2_4-15AA PROTEIN 2 Fc-TM_hRLX2_4-15AA DNA 3 Fc-TM_hRLX2_4-15AA PROTEIN 4 Fc-FQQ_hRLX2_4-15AA DNA 5 Fc-FQQ_hRLX2_4-15AA PROTEIN 6 Fc-YTE_hRLX2_4-15A DNA 7 Fc-YTE_hRLX2_4-15A PROTEIN 8 Fc-YTE-TM-hRLX2-4-15AA DNA 9 Fc-YTE-TM-hRLX2-4-15AA PROTEIN 10 Fc-YTE-FQQ-hRLX2-4-15A DNA 11 Fc-YTE-FQQ-hRLX2-4-15A PROTEIN 12 Fc-G4P_hRLX2_4-15AA DNA 13 Fc-G4P_hRLX2_4-15AA PROTEIN 14 Fc_hRLX2_15-15A DNA 15 Fc_hRLX2_15-15A PROTEIN 16 Fc-TM_hRLX2_15-15AA DNA 17 Fc-TM_hRLX2_15-15AA PROTEIN 18 Fc-FQQ_hRLX2_15-15AA DNA 19 Fc-FQQ_hRLX2_15-15AA PROTEIN 20 Fc-YTE_hRLX2_15-15AA DNA 21 Fc-YTE_hRLX2_15-15AA PROTEIN 22 Fc-YTE-TM_hRLX2_15-15AA DNA 23 Fc-YTE-TM_hRLX2_15-15AA PROTEIN 24 Fc-YTE-FQQ_hRLX2_15-15A DNA 25 Fc-YTE-FQQ_hRLX2_15-15A PROTEIN 26 Fc-G4P_hRLX2_15-15AA DNA 27 Fc-G4P_hRLX2_15-15AA PROTEIN 28 Fc-TMΔTHTΔK_hRLX2_21-15AA DNA 61 Fc-TMΔTHTΔK_hRLX2_21-15AA PROTEIN 62 Fc-TMΔTHTΔK_hRLX2(BA)_21- DNA 63 15AA Fc-TMΔTHTΔK_hRLX2(BA)_21- PROTEIN 64 15AA hRLX2-Fc-TMΔTHTΔK_15-24AA DNA 65 hRLX2-Fc-TMΔTHTΔK_15-24AA PROTEIN 66 hRLX2(BA)-Fc-TMΔTHTΔK_15- DNA 67 24AA hRLX2(BA)-Fc-TMΔTHTΔK_15- PROTEIN 68 24AA Fc-TM DNA 29 Fc-TM PROTEIN 30 Fc-FQQ DNA 31 Fc-FQQ PROTEIN 32 Fc-YTE DNA 33 Fc-YTE PROTEIN 34 Fc-YTE-TM DNA 35 Fc-YTE-TM PROTEIN 36 Fc-YTE-FQQ DNA 37 Fc-YTE-FQQ PROTEIN 38 Fc-G4P DNA 39 Fc-G4P PROTEIN 40 Human relaxin 2 A chain DNA 41 Human relaxin 2 A chain PROTEIN 42 Human relaxin 2 B chain DNA 43 Human relaxin 2 B chain PROTEIN 44 Human relaxin 2 B chain variant DNA 45 Human relaxin 2 B chain variant PROTEIN 46 Human relaxin 2 C peptide DNA 47 Human relaxin 2 C peptide PROTEIN 48 Human relaxin 3 A chain DNA 49 Human relaxin 3 A chain PROTEIN 50 Human relaxin 3 B chain DNA 51 Human relaxin 3 B chain PROTEIN 52 Human relaxin 3 C peptide DNA 53 Human relaxin 3 C peptide PROTEIN 54 Conserved motif RXXXRXXI PROTEIN 55 Connector 4AA: GGSP PROTEIN 56 Connector or linker 15AA: PROTEIN 57 GGGGSGGGGSGGGGS Linker GGGGS PROTEIN 58 Linker A(EAAAK)₅A PROTEIN 59 Conserved motif RXXXRXXV PROTEIN 60 Connector 21AA: PROTEIN 69 (GGGGS)₃GGGGGS Connector 24AA: PROTEIN 70 AAA(GGGGS)₄A

DETAILED DESCRIPTION

The present invention relates to Relaxin fusion polypeptides having the structure A-L-B or B-L-A, in which a Relaxin A chain (A) is linked via a linker polypeptide (L) to a Relaxin B chain (B), and in which the linker polypeptide L is at least 15 amino acids in length. In some embodiments, the Relaxin fusion polypeptides are Relaxin 2 fusion polypeptides. Relaxin 2 fusion polypeptides comprise a Relaxin 2 A chain and a Relaxin 2 B chain.

The present invention is based upon the surprising finding that fusion polypeptides in which the linker polypeptide L comprises at least 15 amino acids have Relaxin activity. Thus, the inventors have found that Relaxin 2 fusion polypeptides in which the C terminus of the A chain is connected with a linker of 15 amino acids to the N-terminus of the B chain exhibit biological activity comparable to Relaxin 2 protein having the A chain and B chain array of a mature Relaxin 2 polypeptide (i.e. without a linker between the A and B chains), such as the Relaxin 2 polypeptide of UniProtKB/Swiss-Prot Accession Number P04090.1.

Similarly, the inventors have found that Relaxin 2 fusion polypeptides in which the C terminus of the B chain is connected with a linker of 15 amino acids to the N-terminus of the A chain exhibit biological activity comparable to Relaxin 2 protein having the A chain and B chain array of a mature Relaxin 2 polypeptide These findings are particularly surprising in view of the teaching in PCT publication WO 2013/004607, in which a linker length of less than fifteen amino acids was found to be necessary for biological activity.

Naturally occurring Relaxins are expressed as prohormones with the structure B-C-A, (where “B” is the B chain, “C” is the C peptide, and “A” is the A chain of Relaxin) and the mature proteins are produced by endoproteolytic cleavage of the prohormone with the Prohormone-Convertase 1 (PC1) and Prohormone-Convertase 2 (PC2) enzymes to remove the C peptide. It will be understood that the fusion polypeptides of the invention do not undergo such endoproteolytic cleavage by PC1 and PC2.

The fusion polypeptides of the invention comprise a Relaxin A chain polypeptide or a variant thereof and a Relaxin B chain polypeptide or a variant thereof. In some embodiments, the Relaxin B chain polypeptide does not have any attachments at its C-terminus. In other words, the Relaxin B chain polypeptide has a free C-terminus.

in other embodiments, the Relaxin A chain polypeptide does not have any attachments at its C-terminus. In other words, the Relaxin A chain polypeptide has a free C-terminus.

The fusion polypeptides may comprise Relaxin A and B chain polypeptides from the group of Relaxins selected from Relaxin 1, Relaxin 2 and Relaxin 3. In some embodiments, the fusion polypeptides comprise Relaxin A and B chain polypeptides from Relaxin 2 or Relaxin 3. Thus, the fusion polypeptides may comprise a Relaxin 2 A or a Relaxin 3 A chain polypeptide or a variant thereof and a Relaxin 2 B or a Relaxin 3 B chain polypeptide or a variant thereof. In some other embodiments, the fusion polypeptides comprise a Relaxin 3 A chain polypeptide or a variant thereof and a Relaxin 3 B chain polypeptide or a variant thereof. In particular, the fusion polypeptides may comprise human Relaxin A and B chain polypeptides.

The fusion polypeptides may comprise a Relaxin 2 A chain polypeptide or a variant thereof and a Relaxin 2 B chain polypeptide or a variant thereof. In particular embodiments, the Relaxin A chain polypeptide comprises a human Relaxin 2 A chain polypeptide or a variant thereof and a human Relaxin 2 B chain polypeptide or a variant thereof. The human Relaxin 2 A chain polypeptide may have the sequence as set forth in SEQ ID NO. 42 or a variant thereof and the human Relaxin 2 B chain polypeptide may have the sequence as set forth in SEQ ID NO. 44 or SEQ ID NO. 46 or variants thereof. In further embodiments, the human Relaxin 2 A chain polypeptide has the sequence as set forth in SEQ ID NO. 42 and the human Relaxin 2 B chain polypeptide has the sequence as set forth in SEQ ID NO. 46.

Relaxin A and B chain variants are known in the art. In addition, guidance on the design of Relaxin A and B chain variants is available to the skilled person. For example, it will be understood that variants may retain those amino acids that are required for Relaxin function. For example, Relaxin 2 B chain variants may comprise the conserved motif Arg-X-X-X-Arg-X-X-Ile (SEQ ID NO. 55) (Claasz et al, 2002, Wilkinson et al., 2005) or Arg-X-X-X-Arg-X-X-Val (SEQ ID NO. 60) (Bathgate et al, 2013). Variants may comprise one or more amino acid substitutions, deletions and/or insertions. For example, Relaxin 2 B chain variants may have one or more additional amino acids selected from Val23, Ala24, Lys54, Arg55 and N-terminal Met compared to SEQ ID NO. 44. Alternatively or in addition, variants may comprise one or more amino acid derivatives. For example, the first amino acid of Relaxin 2 B chain variants may be pyroglutamate.

The terms “protein”, “polypeptide” and “peptide” may be used interchangeably herein to refer to a chain of two or more amino acids linked through peptide bonds.

The fusion polypeptides of the invention may be recombinant fusion polypeptides, i.e. which have been created by recombinant DNA technology. Unlike wild-type Relaxin proteins, the fusion polypeptides of the invention do not require endoproteolytic processing for biological activity.

The Relaxin family peptides mediate their biological effects, at least in part, through the activation of G protein-coupled receptors (GPCRs), and the subsequent stimulation or inhibition of the cAMP signalling pathway by the Gs or Gi protein subunit, respectively. Relaxin 2 is known to activate the GPCR RXFP1 (also known as LGR7) and, to a lesser degree, the GPCR RXFP2 (also known as LGR8), thus stimulating the Gs-cAMP-dependent signalling pathway, leading to an increase in the second messenger molecule cAMP.

As used herein, the term “Relaxin activity” refers to the ability of a Relaxin molecule to bind to a Relaxin receptor, and/or activate said Relaxin receptor and/or initiate a signalling cascade inside the cell. In embodiments in which the Relaxin activity is Relaxin 2 activity, Relaxin activity may refer to the ability to bind and/or activate the receptor RXFP1 and/or RXFP2. In embodiments in which the Relaxin activity is Relaxin 3 activity, Relaxin activity may refer to the ability to bind and/or activate the receptor RXFP1, RXFP3 and/or RXFP4 (Bathgate et al., 2013). The term “Relaxin activity” may be used interchangeably with “biological activity”.

Relaxin activity may be determined by measuring binding of a Relaxin molecule to a Relaxin receptor, and/or by measuring downstream events from binding to a Relaxin receptor.

Relaxin activity may be determined in vitro and/or in vivo. In some embodiments, Relaxin activity is determined in vitro.

Relaxin activity may be determined by measuring the amount and/or presence of a molecule downstream from Relaxin activation of a receptor. For example, Relaxin activity may be determined by measuring cAMP production following Relaxin activation of a receptor. Methods for the detection of Relaxin-induced cAMP generation are known in the art. Such methods include cAMP ELISA and the HitHunter® cAMP assay. Relaxin activity may also be determined by measuring nitric oxide (NO) production following Relaxin activation of a receptor. Relaxin activity may also be determined by measuring the activation of a molecule downstream from Relaxin activation of a receptor. For example, Relaxin activity may be determined by measuring activation of p42/44 MAPK.

Alternatively or in addition, Relaxin activity may be determined by measuring the activation of a known Relaxin target gene. For example, Relaxin activity may be determined by measuring the activation of the transcription of the known Relaxin target gene, VEGF, in THP-1 cells. Methods to determine activation of transcription of a gene are known in the art and include quantitative PCR analysis of the mRNA. The relative expression of VEGF mRNA can be measured by quantitative real-time PCR induction of VEGF transcripts following incubation of THP-1 cells with Relaxin as described in Xiao et al. (2013).

Alternatively or in addition, Relaxin activity may be determined by measuring one or more downstream effects of Relaxin. For example, reduction of cardiac hypertrophy can be measured by echocardiography, left ventricular weight relative to body weight and/or tibia length according to standard methods. In another example, Relaxin activity may be determined by measuring fibrosis reduction by Masson's Trichrome stain. In another example, Relaxin activity may be determined by measuring modulation of connective tissue metabolism, such as the inhibition of profibrotic factors (such as TGF-beta), inhibition of fibroblast proliferation and differentiation, and/or activation of MMP-mediated extracellular matrix degradation (Bathgate et al., 2013).

The activity of the Relaxin fusion polypeptides of the invention may be determined in relation to a reference Relaxin protein. In some embodiments, the reference Relaxin protein is a recombinant protein. The activity of the Relaxin fusion polypeptides may be determined in relation to a reference Relaxin protein having the Relaxin A chain and Relaxin B chain array of a mature Relaxin polypeptide (i.e. without a linker between the A and B chains), such as the Relaxin 2 polypeptide of UniProtKB/Swiss-Prot Accession Number P04090.1). Such Relaxins are commercially available. For example, recombinant human Relaxin 2 having the Relaxin 2 chain A and Relaxin 2 chain B array of mature human Relaxin 2 is available from R&D systems (catalogue number 6586-RN-025). In some embodiments, the reference Relaxin protein has the same A and B Relaxin chains as the A and B Relaxin chains of the fusion polypeptides of the invention or differs from the A and B Relaxin chains of the fusion polypeptides of the invention by up to 10 amino acids, for example 1 or 2 amino acids. In other embodiments, the first amino acid of the B chain of the reference Relaxin 2 is D and this amino acid is deleted in the B chain of the fusion polypeptide of the invention. In further embodiments, when the fusion polypeptide comprises the Relaxin 2 A chain polypeptide of SEQ ID NO. 42 and the Relaxin 2 B chain polypeptide of SEQ ID NO. 44 or 46, the reference Relaxin is recombinant Relaxin 2 having the chain A and chain B array of mature human Relaxin 2 and having the amino acid sequence disclosed under UniProtKB/Swiss-Prot Accession Number P04090.1.

The fusion polypeptides of the invention may be considered to have Relaxin activity if they show at least a proportion of the activity of a reference Relaxin protein. For example, a fusion polypeptide may be considered to have Relaxin activity if it has at least about half of the activity of a reference Relaxin protein. Alternatively, a fusion polypeptide of the invention may be considered to have Relaxin activity if the ratio of the activity of said fusion polypeptide over the activity of a reference Relaxin protein is comprised between 1 and about 10⁵, between 1 and about 10⁴, between about 1 and about 10³, between about 1 and about 100, between about 1 and about 50, between about 1 and about 20, between about 1 and about 15, between about 1 and about 10, or between about 1 and about 5. Alternatively, a fusion polypeptide of the invention may be considered to have Relaxin activity if the ratio of the activity of said fusion polypeptide over the activity of a reference Relaxin protein is comprised between about 10⁻⁵ and about 1, between about 10⁻⁴ and about 1, between about 10⁻³ and about 1, between about 10⁻² and about 1, between about 1/50 and about 1, between about 1/20 and about 1, between about 1/15 and about 1, between about 1/10 and about 1, between about ⅕ and about 1.

In certain embodiments, the ratio of Relaxin activity of the fusion polypeptide of the invention over the Relaxin activity of the reference Relaxin protein is comprised between about 10⁻⁵ and about 10⁵.

In some embodiments, the ratio of the activity of a fusion polypeptide of the invention over the activity of a reference Relaxin protein is comprised between about 1 and about 100, for instance between about 1 and about 50, between about 1 and about 20, or between about 1 and about 15, or between about 1 and about 10, or between about 1 and about 5.

In other embodiments, the ratio of the activity of the fusion polypeptide of the invention over the activity of a reference Relaxin protein is comprised between about 10⁻² and about 1, or between about 1/50 and about 1, for instance between about 1/20 and about 1, between about 1/15 and about 1, between about 1/10 and about 1, or between about ⅕ and about 1.

In still other embodiments, the ratio of the activity of the fusion polypeptide of the invention over the activity of a reference Relaxin protein is about 1.

Relaxin activity may be determined as an EC50 value. As used herein the term “EC50” (half maximal effective concentration) refers to the effective concentration of a therapeutic compound which induces a response halfway between the baseline and maximum after a specified exposure time.

The inventors have shown that the fusion polypeptides of the invention have Relaxin activity as does a Relaxin protein having the Relaxin 2 A chain and Relaxin 2 B chain array of a mature Relaxin 2 polypeptide (i.e. without a linker between the A and B chain) such as the recombinant Relaxin protein from R&D systems (catalogue number 6586-RN-025). As shown in the experimental section, the ratio of the average EC50 value determined for some fusion polypeptides of the invention over the average EC50 value determined for the recombinant Relaxin protein from R&D systems (catalogue number 6586-RN-025) is comprised between about 1 and about 100. Accordingly, the fusion polypeptides of the invention may have an EC50 value that is the same or substantially the same as the EC50 value of a reference Relaxin protein. Alternatively, the fusion polypeptides may have an EC50 value that is greater than the EC50 value of a reference Relaxin protein. Alternatively, the fusion polypeptides may have an EC50 value that is less than the EC50 value of a reference Relaxin protein.

The fusion polypeptides of the invention may have an EC50 value that is such that the ratio of the EC50 of said fusion polypeptide over the EC50 of a reference Relaxin protein is comprised between 1 and about 10⁵, between 1 and about 10⁴, between about 1 and about 10³, between about 1 and about 100, between about 1 and about 50, between about 1 and about 20, between about 1 and about 15, between about 1 and about 10, or between about 1 and about 5. Alternatively, a fusion polypeptide of the invention may have an EC50 value that is such that the ratio of the EC50 of said fusion polypeptide over the EC50 of a reference Relaxin protein is comprised between about 10⁻⁵ and about 1, between about 10⁻⁴ and about 1, between about 10⁻³ and about 1, between about 1/100 and about 1, between about 1/50 and about 1, between about 1/20 and about 1, between about 1/15 and about 1, between about 1/10 and about 1, between about ⅕ and about 1. In certain embodiments, the ratio of the EC50 value of the fusion polypeptide of the invention over the EC50 value of the reference Relaxin protein is comprised between about 10⁻⁵ and about 10⁵.

In some embodiments, the Relaxin fusion polypeptides have an EC50 value of between about 1·10⁻¹¹ and about 1·10⁻⁷ M, for instance between about 1·10⁻¹⁰ and about 1·10⁻⁸ M, or between about 1·10⁻¹⁰ and about 8·10⁻⁹ M, or between about 1·10⁻¹⁰ and about 5·10⁻⁹ M or between about 1·10⁻¹⁰ and about 1·10⁻⁹ M.

The linker polypeptide L of the fusion polypeptides is at least 15 amino acid residues in length. In some embodiments, the linker polypeptide L is at least 16, 17, 18, 19 or 20 amino acid residues in length. The linker polypeptide L can be of 15 to 30 amino acid residues in length, for instance the linker polypeptide L can be of 15 to 25 amino acid residues in length or of 15 to 20 amino acid residues in length. In a particular embodiment, the linker polypeptide L does not have an amino acid sequence length of 102 amino acids. In another embodiment, said linker polypeptide L has an amino acid sequence length of less than 100, less than 90, less than 80, less than 70, less than 60, or less than 50 amino acids.

The linker polypeptide L can be composed of any amino acid. In some embodiments, the linker polypeptide L comprises glycine and serine residues such as those described in Chen et al., 2013. In further embodiments, the linker polypeptide L comprises the motif (GGGGS)n (repeats of SEQ ID NO. 58), wherein n may be between 1 and 5, for instance wherein n is 4. In other embodiments, the linker polypeptide L comprises or consists of the sequence GGGGSGGGGSGGGGS (SEQ ID NO. 57). In alternative embodiments, the linker polypeptide L comprises or consists of the sequence A(EAAAK)nA (SEQ ID NO. 59), wherein n is 5, as described in Chen et al., 2013.

The linker polypeptide L may have an amino acid sequence that differs from Relaxin C peptide, in particular from human Relaxin 2 C peptide of amino acid sequence SEQ ID NO. 48. In particular, the linker polypeptide L may have less than 80%, less than 70%, less than 60%, less than 50%, less than 40% identity with a Relaxin C peptide, such as human Relaxin 2 C peptide of amino acid sequence SEQ ID NO. 48.

The linker polypeptide L may be an artificial polypeptide, e.g. a polypeptide that is synthesised by chemical peptide synthesis.

The fusion polypeptides of the invention also comprise a half-life extending moiety. Thus, in some embodiments the fusion polypeptides of the invention have an extended half-life compared to the corresponding reference Relaxin. It will be recognised that an extended half-life is advantageous, as it permits the therapeutic proteins to be administered according to a safe and convenient dosing schedule, e.g. lower doses that can be administered less frequently. Moreover, the achievement of lower doses may provide further advantages such as the provision of an improved safety profile and/or the activation of multiple mechanisms of action in vivo.

The inventors have shown that fusion polypeptides of the invention having a half-life extending moiety possess Relaxin activity and at the same time have extended half-lives compared to reference Relaxin. For example, the inventors have shown that fusion polypeptides having a half-life extending moiety according to some embodiments of the invention have a half-life of at least 2 days in rat and mouse models (see Examples 5 and 6). In comparison, the half-life of human Relaxin 2 following IV administration is about 0.09+/−0.04 hours, i.e. 5.4+/−2.4 minutes in humans (Chen et al. 1993).

As used herein, the term “half-life” is used to refer to the time taken for the concentration of fusion polypeptide in plasma to decline to 50% of its original level. The “half-life” of a polypeptide in plasma may depend on different factors such as the size of the polypeptide, its stability, its clearance rate, turnover rate, in vivo proteolytic degradation, the rate of absorption by the body or specific tissues, etc. Methods to determine the half-life of proteins are known in the art and are described in the Examples below.

The half-life extending moiety may be attached at the N-terminus or the C-terminus of the fusion polypeptide. In some embodiments, the half-life extending moiety is attached at the N-terminus of the fusion polypeptide. In other embodiments, the half-life extending moiety is attached at the C-terminus of the fusion polypeptide.

In some embodiments, the half-life extending moiety is a proteinaceous half-life extending moiety. The proteinaceous half-life extending moiety may be selected from the group consisting of an Fc region of an immunoglobulin, albumin-binding domain, serum albumin and transferrin. In other embodiments, the half-life extending moiety is an Fc region.

In further embodiments, the half-life extending moiety is a chemical entity that is not a protein or peptide, such as polyethylene glycol (PEG) polymer chains which may be covalently or non-covalently attached to the rest of the fusion polypeptide of the invention. PEGylation, that is the process of attaching said PEG polymer chains to a molecule, can be carried out according to methods well known in the art.

The term “Fc region” defines the C-terminal region of an immunoglobulin heavy chain, which may be generated by papain digestion of an intact antibody. The Fc region of an immunoglobulin generally comprises two constant domains, a CH2 domain and a CH3 domain, and optionally comprises a CH4 domain.

The Fc region may be derived from an immunoglobulin from any species. In some embodiments, the Fc region is derived from a human immunoglobulin. In further embodiments, the Fc region is derived from a human IgG immunoglobulin. In particular embodiments, the Fc region is derived from a human IgG1 immunoglobulin. In other embodiments, the Fc region is derived from a human IgG4 immunoglobulin.

In some embodiments, the Fc region comprises a native Fc sequence, i.e. an amino acid sequence identical to the amino acid sequence found in nature. In alternative embodiments, the Fc region comprises a variant Fc sequence, i.e. an amino acid sequence that differs from the amino acid sequence by at least one amino acid modification. The Fc region may be modified to e.g. increase the affinity of the IgG molecule for the FcRn. PCT publication WO 02/060919 discloses modified immunoglobulins comprising an Fc region having one or more amino acid modifications and is incorporated herein in its entirety by reference. For a Fc region derived from an IgG4 immunoglobulin, the Fc region may also be modified to reduce Fab arm exchange (the dynamic process by which IgG4 antibodies can exchange half-molecules), e.g. by introducing a S228P modification in the IgG4 amino acid sequence, wherein the amino acid numbering is according to the EU index as in Kabat. Methods of making Fc regions with one or more amino acid modifications are known in the art.

In some embodiments, the Fc region comprises a human IgG sequence, in particular a human IgG1 sequence, comprising at least one of the following combinations of amino acid modifications:

-   -   (i) Fc-YTE (M252Y, S254T, T256E);     -   (ii) Fc-FQQ (L234F, L235Q, K322Q);     -   (iii) Fc-TM (L234F, L235E, P331S),     -   (iv) Fc-YTE-FQQ (M252Y, S254T, T256E, L234F, L235Q, K322Q);     -   (v) Fc-YTE-TM ((M252Y, S254T, T256E, L234F, L235E, P331S),     -   (vi) Fc-TM-ΔTHT (L234F, L235E, P331S, D221G, K222G, T223G,         H224S, T225A),     -   (vii) Fc-TM-ΔTHTΔK (L234F, L235E, P331S, D221G, K222G, T223G,         H224S, T225A, ΔK447),         wherein the amino acid numbering is according to the EU index as         in Kabat.

In further embodiments, the Fc region comprises a human IgG4 sequence. In particular the Fc region comprises a human IgG4 sequence wherein a Serine is modified into a Proline at position 228 (“5228P”), wherein the amino acid numbering is according to the EU index as in Kabat, said modified Fc region is abbreviated herewith as “Fc-G4P”. In still further embodiments, the Fc region derived from an IgG4 comprises the S228P modification and at least one of the following combinations of amino acid modifications:

-   -   (i) Fc-YTE (M252Y, S254T, T256E);     -   (ii) Fc-FQQ (L234F, L235Q, K322Q);     -   (iii) Fc-TM (L234F, L235E, P331S),     -   (iv) Fc-YTE-FQQ (M252Y, S254T, T256E, L234F, L235Q, K322Q);     -   (v) Fc-YTE-TM ((M252Y, S254T, T256E, L234F, L235E, P331S),     -   (vi) Fc-TM-ΔTHT (L234F, L235E, P331S, D221G, K222G, T223G,         H224S, T225A),     -   (vii) Fc-TM-ΔTHTΔK (L234F, L235E, P331S, D221G, K222G, T223G,         H224S, T225A, ΔK447),         wherein the amino acid numbering is according to the EU index as         in Kabat.

The term “EU index as in Kabat” refers to the numbering system of the human IgGl EU antibody described in Kabat et al, Sequences of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991). AH amino acid positions referenced in the present application refer to EU index positions. For example, both “L234” and “EU L234” refer to the amino acid leucine at position 234 according to the EU index as set forth in Kabat.

According to an aspect of the invention, there is provided a modified immunoglobulin comprising an immunoglobulin constant domain comprising one or more amino acid modifications relative to a wild-type immunoglobulin constant domain, wherein the one or more amino acid modifications are at one or more of positions 234, 235 and 331, wherein the amino acid numbering is according to the EU index as in Kabat. According to another aspect, there is provided a modified immunoglobulin comprising an immunoglobulin constant domain comprising one or more amino acid modifications relative to a wild-type immunoglobulin constant domain, wherein the one or more amino acid modifications are at one or more of positions 234, 235 and 322, wherein the amino acid numbering is according to the EU index as in Kabat. According to another aspect of the invention, there is provided a modified immunoglobulin comprising an immunoglobulin constant domain comprising one or more amino acid modifications relative to a wild-type immunoglobulin constant domain, wherein the one or more amino acid modifications are at one or more of positions 221, 222, 223, 224, 225, and 447, wherein the amino acid numbering is according to the EU index as in Kabat. According to still further aspects of the invention, there is provided a modified immunoglobulin comprising an immunoglobulin constant domain comprising one or more amino acid modifications relative to a wild-type immunoglobulin constant domain, wherein the one or more amino acid modifications are at one or more of positions 221, 222, 223, 224, 225, 234, 235, 331 and 447, wherein the amino acid numbering is according to the EU index as in Kabat. In some embodiments, the one or more amino acid modifications abolish the effector function of Fc region and/or reduce or circumvent cytotoxicity, for example antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC).

According to an aspect of the invention, there is provided a modified immunoglobulin comprising an immunoglobulin constant domain comprising one or more amino acid modifications relative to a wild-type immunoglobulin constant domain, wherein the one or more amino acid modifications are at one or more of positions 252, 254 and 256, wherein the amino acid numbering is according to the EU index as in Kabat. In some embodiments, the one or more amino acid modifications increase the half-life of the fusion polypeptide.

In some embodiments, the one or more amino acid modifications are amino acid substitutions.

In other embodiments, the one or more amino acid modifications are amino acid deletions.

In further embodiments, the one or more amino acid substitutions include one or more of: substitution with phenylalanine at position 234, substitution with glutamic acid at position 235 and/or substitution with serine at position 331. In particular embodiments, the modified immunoglobulin comprises the amino acid substitutions of phenylalanine at position 234, glutamic acid at position 235 and serine at position 331. The amino acid numbering mentioned here is according to the EU index as in Kabat.

In further embodiments, the one or more amino acid substitutions include one or more of: substitution with phenylalanine at position 234, substitution with glutamine at position 235 and/or substitution with glutamine at position 322. In particular embodiments, the modified immunoglobulin comprises the amino acid substitutions of phenylalanine at position 234, glutamine at position 235 and glutamine at position 322. The amino acid numbering mentioned here is according to the EU index as in Kabat.

In other embodiments, the one or more amino acid substitutions include one or more of: substitution with tyrosine at position 252, substitution with threonine at position 254 and/or substitution with glutamic acid at position 256. In particular embodiments, the modified immunoglobulin comprises the amino acid substitutions of tyrosine at position 252, threonine at position 254 and glutamic acid at position 256. The amino acid numbering mentioned here is according to the EU index as in Kabat.

In still other embodiments, the one or more amino acid modifications include one or more of: substitution with glycine at position 221, substitution with glycine at position 222, substitution with glycine at position 223, substitution with serine at position 224, substitution with alanine at position 225, and/or deletion of lysine at position 447, wherein the amino acid numbering is according to the EU index as in Kabat.

In still other embodiments, the one or more amino acid modifications include one or more of: substitution with glycine at position 221, substitution with glycine at position 222, substitution with glycine at position 223, substitution with serine at position 224, substitution with alanine at position 225, substitution with phenylalanine at position 234, substitution with glutamic acid at position 235, substitution with serine at position 331, and/or deletion of lysine at position 447, wherein the amino acid numbering is according to the EU index as in Kabat.

It will be understood that the modified immunoglobulin may further comprise other amino acid modifications, such as the other amino acid modifications detailed herein, or any combination thereof.

Methods for attaching the half-life extending moiety to the fusion polypeptide are known in the art. For example, the half-life extending moiety may be attached by chemical conjugation or recombinant technology. The half-life extending moiety may be attached to the fusion polypeptide directly or through a connector polypeptide. The use of a connector polypeptide may be particularly appropriate when the fusion polypeptide comprises a proteinaceous half-life extending moiety such as an Fc region.

The connector polypeptide may be any suitable length, for example between about 1 and 100 amino acids in length, between about 1 and 50 amino acids in length, between about 1 and 25 amino acids in length, between about 1 and 15 amino acids in length or between about 4 and 15 amino acids in length. In some embodiments, the connector is between 4 and 15 amino acids in length. For instance, a connector can be of 4, 5, or 15 amino acids in length. In other embodiments, the connector is between 15 and 25 amino acids in length, for instance a connector can be of 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 amino acids in length.

The connector polypeptide may comprise any amino acid. Connector polypeptides suitable for the invention may include any of those described in Chen et al., 2013. In some embodiments, the connector comprises glycine and serine residues such as described in Chen et al., 2013. In further embodiments, the connector polypeptide comprises one or more repeats of the motif GGGGS (SEQ ID NO. 58). For example, the connector polypeptide may comprise the sequence GGGGSGGGGSGGGGS (SEQ ID NO. 57). In further embodiments, the connector polypeptide has a Proline residue at the C- and/or N-terminal end. In other embodiments, the connector polypeptide has one or more, for instance 1 to 3, alanine residue(s) at the C- and/or N-terminal end. In some embodiments, the connector polypeptide comprises or consists of the same sequence as the linker polypeptide L of the fusion polypeptide.

Examples of connectors include: GGSP (SEQ ID NO. 56), GGGGSGGGGSGGGGS (SEQ ID NO. 57), GGGGSGGGGSGGGGSGGGGGS (SEQ ID NO. 69), AAAGGGGSGGGGSGGGGSGGGGSA (SEQ ID NO. 70).

The fusion polypeptides of the invention may be single chain Relaxin fusion polypeptides.

In some embodiments, the fusion polypeptides of the invention have the structure

-   -   Fc-Cn-A-L-B or Fc-Cn-B-L-A         wherein A is a Relaxin A chain polypeptide or a variant thereof;         B is a Relaxin B chain polypeptide or a variant thereof; L is a         linker polypeptide comprising at least 15 amino acids; Cn is a         connector polypeptide; and Fc is the Fc region of an         immunoglobulin heavy chain.

In some embodiments, the fusion polypeptides of the invention have the structure

-   -   A-L-B-Cn-Fc or B-L-A-Cn-Fc         wherein A is a Relaxin A chain polypeptide or a variant thereof;         B is a Relaxin B chain polypeptide or a variant thereof; L is a         linker polypeptide comprising at least 15 amino acids; Cn is a         connector polypeptide; and Fc is the Fc region of an         immunoglobulin heavy chain.

In further embodiments, the fusion polypeptides of the invention are one or more of the fusion polypeptides set forth in Table 1 and FIGS. 1 to 19 . In FIGS. 2 to 19 , the linker L is indicated by double underlining, the connector Cn is indicated by single underlining, and nucleotide and amino acid substitutions are indicated in bold and by bold underlining.

TABLE 1 Exemplary fusion polypeptides of the invention SEQ ID NO. of a nucleic acid FIG. SEQ encoding said Fusion polypeptide No. ID NO. fusion polypeptide Fc_hRLX2_4-15AA 2 2 1 Fc-TM_hRLX2_4-15AA 3 4 3 Fc-FQQ_hRLX2 4-15AA 4 6 5 Fc_YTE-hRLX2 4-15A 5 8 7 Fc-YTE-TM_hRLX2_4-15AA 6 10 9 Fc-YTE-FQQ_hRLX2_4-15A 7 12 11 Fc-G4P hRLX2 4-15AA 8 14 13 Fc_hRLX2_15-15AA 9 16 15 Fc-TM_hRLX2_15-15AA 10 18 17 Fc-FQQ_hRLX2_15-15AA 11 20 19 Fc-YTE_hRLX2_15-15AA 12 22 21 Fc-YTE-TM_hRLX2_15-15AA 13 24 23 Fc-YTE-FQQ_hRLX2_15-15A 14 26 25 Fc-G4P_hRLX2_15-15AA 15 28 27 Fc-TMΔTHTΔK_hRLX2_21-15AA 16 62 61 Fc-TMΔTHTΔK_hRLX2(BA)_21-15AA 17 64 63 hRLX2-Fc-TMΔTHTΔK_15-24AA 18 66 65 hRLX2(BA)-Fc-TMΔTHTΔK_15-24AA 19 68 67

The fusion polypeptides of the invention may be produced by any method known in the art. In some embodiments, the fusion polypeptides of the invention are produced by recombinant expression of a nucleic acid molecule encoding a fusion polypeptide in a host cell.

Accordingly, the present invention provides nucleic acid molecules, e.g. DNA molecules, that encode a fusion polypeptide of the invention, as well as vectors comprising the nucleic acid molecules of the invention, and host cells comprising such nucleic acid molecules and vectors.

Sequences of the nucleic acid molecules of the invention according to some embodiments are set out in FIGS. 2 to 19 and in Table 1.

Methods that are known to those skilled in the art can be used to construct expression vectors containing the nucleic acid molecules of the invention. Suitable vectors include, for example, plasmids, phagemids, phages or viral vectors.

Vectors containing the nucleic acid molecules of the invention may be transferred to a host cell by conventional techniques. Suitable host cells are known in the art. In some embodiments, the host cells are mammalian cells such as HEK293 cells or CHO cells.

The transfected cells may be cultured by conventional techniques to produce the fusion polypeptides of the invention.

Once a fusion polypeptide of the invention has been produced, for example by recombinant expression, it may be purified by any method known in the art. Exemplary protein purification techniques include chromatography (e.g. ion exchange, affinity and/or sizing column chromatography), centrifugation and differential solubility. The present invention provides isolated fusion polypeptides that have been separated from the cell culture, optionally by at least one purification step.

The fusion polypeptides of the invention may be provided in a pharmaceutical composition.

The pharmaceutical compositions of the invention may comprise one or more excipient(s). Pharmaceutically acceptable excipients are known in the art, see for instance Remington's Pharmaceutical Sciences (by Joseph P. Remington, 18th ed., Mack Publishing Co., Easton, Pa.), which is incorporated herein in its entirety.

The present invention encompasses therapies which involve administering the fusion polypeptides of the invention to an animal, in particular a mammal, for instance a human, for preventing, treating, or ameliorating symptoms associated with a disease, disorder, or infection.

Accordingly, the fusion polypeptides or a pharmaceutical composition of the invention may be used in therapy, for example for treating a disease or disorder. Also provided is a method of treating a disease or disorder comprising administering to a subject or patient in need thereof a therapeutically effective amount of the fusion polypeptides of the invention. The use or method may comprise administering a therapeutically effective schedule that has less frequent doses of the fusion polypeptides of the invention than the therapeutically effective dosing schedule of a wild-type Relaxin molecule.

It will be understood that the fusion polypeptides of the invention may be used in the treatment of cardiovascular diseases, for example for the treatment of heart failure.

As used herein, the term “heart failure” includes acute heart failure, chronic heart failure (CHF) and acute decompensated heart failure (ADHF). The term “heart failure” may also include more specific diagnoses such as heart failure with preserved ejection fraction (HFpEF), heart failure with mid-range ejection fraction or heart failure with reduced ejection fraction (HFrEF).

The fusion polypeptides of the invention may also be used in the treatment of kidney disease, lung disease and fibrotic disorders, for example fibrotic disorders of the kidney, heart, lung and liver, and in wound healing (Sherwood, 2004). The fusion polypeptides of the invention may also be used in the reversal of insulin resistance in diabetic patients (Bonner et al., 2013).

The fusion polypeptides and/or pharmaceutical compositions of the invention are suitable for parenteral administration to a subject or patient. In some embodiments the subject or patient is a mammal, in particular a human.

Wild-type human Relaxin 2 has a half-life of minutes in vivo. As a consequence, it has to be administered by continuous intravenous infusion in hospitalized patients and presents severe side effects including blood pressure drop. In contrast, it will be understood that embodiments of the fusion polypeptides and/or pharmaceutical compositions of the invention may be administered by injection, such as by intravenous, subcutaneous or intramuscular injection, to a subject or patient. In some embodiments, the fusion polypeptides and/or pharmaceutical compositions are administered by subcutaneous injection. Administration by injection, such as by subcutaneous injection, offers the advantage of better comfort for the subject or patient and the opportunity to administer to a subject or patient outside of a hospital setting. In some embodiments the fusion polypeptide or pharmaceutical composition is administered by self-administration.

In some embodiments, the fusion polypeptides of the invention have an increased half-life compared to wild-type Relaxin, which permits lower overall exposure based on molar concentration. For example, the fusion polypeptides of the invention may be administered less frequently than wild-type Relaxin, thus providing a more convenient dosing schedule.

The present invention provides a kit comprising the pharmaceutical compositions of the invention. The kit may comprise a package containing the pharmaceutical compositions of the invention and instructions. In some embodiments, the pharmaceutical compositions of the invention are formulated in single dose vials or a container closure system (e.g. pre-filled syringe). Optionally associated with such container(s) can be a notice in the form prescribed by a governmental agency regulating the manufacture, use or sale of pharmaceuticals or biological products, which notice reflects approval by the agency of manufacture, use or sale for human administration.

As used herein, the articles “a” and “an” may refer to one or to more than one (e.g. to at least one) of the grammatical object of the article.

“About” may generally mean an acceptable degree of error for the quantity measured given the nature or precision of the measurements. Exemplary degrees of error are within 20 percent (%), typically, within 10%, and more typically, within 5% of a given value or range of values.

Embodiments described herein as “comprising” one or more features may also be considered as disclosure of the corresponding embodiments “consisting of” such features.

The term “pharmaceutically acceptable” as used herein means approved by a regulatory agency of the Federal or a state government, or listed in the U.S. Pharmacopeia, European Pharmacopeia or other generally recognized pharmacopeia for use in animals, and more particularly in humans.

Concentrations, amounts, volumes, percentages and other numerical values may be presented herein in a range format. It is also to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.

The above embodiments are to be understood as illustrative examples. Further embodiments are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

In the context of the present disclosure other examples and variations of the fusion polypeptides and methods described herein will be apparent to a person of skill in the art. Other examples and variations are within the scope of the disclosure, as set out in the appended claims.

All documents cited herein are each entirely incorporated by reference herein, including all data, tables, figures, and text presented in the cited documents.

EXAMPLES Example 1: Constructs

Some DNA constructs were created to express various IgG1-Fc/connector/Relaxin 2 A chain/linker/Relaxin 2 B chain fusion polypeptides. In these constructs, the connector was either 4 amino acids (GGSP) or 15 amino acids (GGGGSGGGGSGGGGS) in length and the linker was 15 amino acids (GGGGSGGGGSGGGGS) in length. The Fc moiety was either native wild-type human IgG1 Fc moiety (abbreviated “hFc-G1”) or a mutated form of human IgG1 Fc moiety comprising one or several combinations of the following mutations:

-   -   (i) M252Y, S254T, T256E (abbreviated “YTE”). The Fc moiety         comprising the YTE mutations is abbreviated “hFc-G1-YTE”.     -   (ii) L234F, L235Q, K322Q (abbreviated “FQQ”). The Fc moiety         comprising the FQQ mutations is abbreviated “hFc-G1-FQQ”. The Fc         moiety comprising both the YTE and the FQQ mutations is         abbreviated “hFc-G1-YTE-FQQ”.     -   (iii) L234F, L235E, P331S (abbreviated “TM”). The Fc moiety         comprising the TM mutations is abbreviated “hFc-G1-TM”. The Fc         moiety comprising both the YTE and the TM mutations is         abbreviated “hFc-G1-YTE-TM”.

In these constructs, the A chain was the native wild-type A chain of human Relaxin 2 (SEQ ID NO. 42) and the B chain was a B chain variant (SEQ ID NO. 46) corresponding to the native wild-type B chain of human Relaxin 2 (SEQ ID NO. 44) lacking the first amino acid (D).

The DNA for the fusion polypeptides with native human IgG-1 Fc sequence was synthesized by GeneArt® (Regensburg, Germany) and supplied as plasmid DNA. The human IgG1 Fc gene sequence was removed from GeneArt® plasmid by restriction enzyme digestion with XbaI and NotI and cloned into the pHOE vector using the same restriction digestions with XbaI and NotI. The pHOE vector was designed for expressing the heavy chain of human antibody IgG1. This cloning strategy removed all the vector antibody sequence but preserved the intron between the signal peptide and Fc sequence.

The required human IgG1 Fc mutations (YTE, FQQ and TM) occur within a 300 bp KasI restriction fragment located within the human IgG1 Fc. The KasI fragment with the appropriate mutations was synthesized by IDT (Coralville, Iowa) as a GeneBlock. The human relaxin-2 plasmid with native Fc fusion was digested with KasI and the KasI GeneBlock was cloned in pHOE vector using the NEBuilder HiFi Assembly Master Mix (NEB #E2621S) for seamless cloning.

Fc-hRLX2-4-15AA and Fc-hRLX2-15-15AA

The Fc-hRLX2-4-15AA and Fc-hRLX2-15-15AA gene sequences were synthesized by GeneArt® (Regensburg, Germany) and supplied as plasmid DNA. The gene sequences were removed from GeneArt® plasmid by restriction enzyme digestion with XbaI and NotI and independently cloned into the pHOE vector using the same restriction sites, leading to pOE-Fc-hRLX2-4-15AA plasmid and pOE-Fc-hRLX2-15-15AA plasmid, respectively. The pHOE vector is used for expressing the heavy chain portion of human IgG1. This cloning strategy removed all the vector antibody sequence but preserved the intron between the signal peptide and Fc sequence.

Fc-YTE-hRLX2-4-15AA and Fc-YTE-hRLX2-15-15AA

The YTE mutations (M252Y/S254T/T256E) occur within a 300 bp KasI fragment located in the human IgG1 Fc. The KasI fragment with appropriate mutations was synthesized by IDT (Coralville, Iowa) as a GeneBlock. The pOE-Fc-hRLX2-4-15AA plasmid and pOE-Fc-hRLX2-15-15AA plasmid were independently digested with KasI and the KasI GeneBlock was cloned into the above plasmids using the NEBuilder HiFi Assembly Master Mix (NEB #E2621S) for seamless cloning.

Fc-YTE-TM-hRLX2-4-15AA and Fc-YTE-TM-hRLX2-15-15AA

The YTE-TM mutations (M252Y/S254T/T256E, L234F/L235E/P331S) occur within a 300 bp KasI fragment located in the human IgG1 Fc. The KasI fragment with appropriate mutations was synthesized by IDT (Coralville, Iowa) as a GeneBlock. The pOE-Fc-hRLX2-4-15AA plasmid and pOE-Fc-hRLX2-15-15AA plasmid were independently digested with KasI and the KasI GeneBlock was cloned into the empty vectors using the NEBuilder HiFi Assembly Master Mix (NEB #E2621S) for seamless cloning. The 3′ KasI site is destroyed in these plasmids.

Fc-YTE-FQQ-hRLX2-4-15AA and Fc-YTE-FQQ-hRLX2-15-15AA

The YTE-FQQ mutations (M252Y/S254T/T256E, L234F/L235Q/K322Q) occur within a 300 bp KasI fragment located in the human IgG1 Fc. The KasI fragment with appropriate mutations was synthesized by IDT® (Coralville, Iowa) as a GeneBlock. The pOE-Fc-hRLX2-4-15AA plasmid and pOE-Fc-hRLX2-15-15AA plasmid were independently digested with KasI and the KasI GeneBlock was cloned into the empty vectors using the NEBuilder HiFi Assembly Master Mix (NEB #E2621S) for seamless cloning.

Some other DNA constructs were created to express Relaxin 2 as a Fc fusion polypeptide with connectors longer than 15 amino acids in length, as well as Relaxin 2 fusion proteins comprising a Fc part situated at either the N- or C-terminus of the fusion protein, and with two possible orientations for the relaxin chains (A-L-B or B-L-A).

In these other constructs, the connector was either 21 amino acids (GGGGSGGGGSGGGGSGGGGGS) or 24 amino acids (AAAGGGGSGGGGSGGGGSGGGGSA) and the linker was 15 amino acids (GGGGSGGGGSGGGGS) in length.

The Fc moiety was a mutated form of human IgG1 Fc moiety, abbreviated “hFc-G1-TM-ΔTHT-ΔK”, comprising the following mutations:

-   -   (i) L234F, L235E, P331S (abbreviated “TM”),     -   (ii) D221G, K222G, T223G, H224S, T225A (abbreviated “ΔTHT”),     -   (iii) Deletion of K447 (abbreviated “AK”).

In these other constructs, the A chain was the native wild-type A chain of human Relaxin 2 (SEQ ID NO. 42) and the B chain was a B chain variant (SEQ ID NO: 46) corresponding to the native wild-type B chain of human Relaxin 2 (SEQ ID NO: 44) lacking the first amino acid (D).

The DNA inserts for constructs Fc-TMΔTHTΔK_hRLX2_21-15AA (construct 15 in FIG. 1 ) and hRLX2-Fc-TMΔTHTΔK_15-24AA (construct 17 in FIG. 1 ) were generated by PCR amplification of the DNA molecule of construct 8 in FIG. 1 (Fc_hRLX2_15-15AA). The DNA inserts for constructs (Fc-TMΔTHTΔK_hRLX2(BA)_21-15AA (construct 16 in FIG. 1 ) and hRLX2(BA)-Fc-TMΔTHTΔK_15-24AA (construct 18 in FIG. 1 ) were synthesized by GenScript® (Piscataway, USA) and then amplified by PCR before digestion with restriction enzymes. The PCR amplicons for constructs 15 and 16 were digested by the restriction enzymes BamHI and EcoRI. The PCR amplicons for constructs 17 and 18 were digested by the restriction enzymes NgoMIV and NotI. The digested inserts were ligated into the plasmid pepFc (derived from pOE). The plasmids were digested with BamHI and EcoRI for fusion at the C-terminus of the Fc; or with NgoMIV and NotI for fusion at the N-terminus. The Quick ligation kit (NEB) was used to ligate the DNA inserts into the plasmids.

The Relaxin Fc fusions were expressed in CHO cells by standard methods as described in Daramola, et al., 2014. The fusion proteins were purified from the supernatant using an ÄKTAxpress system by affinity chromatography with MabSelectSuRe columns. Columns were equilibrated in 1×DPBS (Gibco, Invitrogen. Cat No: 14190-094). After loading of the supernatant, the column was washed with 1×DPBS to remove molecules which do not bind specifically to the column. Elution of the Fc fusions was achieved using a solution of 0.1M glycine at pH2.7. The purified proteins were buffer exchanged to 1×DPBS. The protein concentrations were determined using absorption at 280 nm. The purified proteins were then analysed by SDS-PAGE and SEC-HPLC (TSKgel G3000SWXL column) to assess purity and monomeric content.

FIG. 1 provides a schematic representation and abbreviated names of some of the Fc human Relaxin 2 fusion polypeptides of the invention.

Example 2: In Vitro Activity of Fc-Relaxin-2 Fusion Polypeptides (In Vitro cAMP Assay)

An in vitro cell-based assay was used to measure the activity of Relaxin 2 fusion polypeptides generated in Example 1. The assay measured the ability of the fusion polypeptides (Fc-hRLX2-4-15AA and Fc-hRLX2-15-15AA) to stimulate cAMP production.

The HitHunter® cAMP assay from DiscoverX (catalogue number 90-0075, Fremont, Calif.) was used to measure the cAMP produced after ligand stimulation with the Relaxin 2 fusion polypeptides. The assay was performed based on the manufacturer's protocol. Briefly, cells from an RXFP1 expression cell line, CHO-K1 RXFP1 Gs, (DiscoverX catalogue number 95-0127C2, Fremont, Calif.), were seeded at 20,000 cells/well in 100 μL/well of F12K media (Gibco, Cat #21127022), supplemented with 1% antibiotics, 0.8 mg/ml Geneticin, and 10% fetal bovine serum using a MultiDrop Combi dispenser (Thermo Scientific, Waltham, Mass.) and allowed to attach overnight at 37° C. in 5% CO₂ incubator. Following incubation, plates were washed with 100 μL/well of F12K serum-free media. Wash media was removed and plates were ready to assay after addition of 20 μL/well of F12K serum-free media. For testing sample preparation, in a separate 96-U bottom plate three-fold dilutions of Relaxin 2 fusion polypeptides, and recombinant human Relaxin-2 (R&D Systems, catalogue number 6586-RN-025) as positive control, were made in replicates. From the diluted and titrated sample plate, 10 μL from each well was transferred into the assay plate, incubated at 37° C. for 30 minutes. Post incubation, 10 μL/well of antibody reagent (from the HitHunter® kit) was added, immediately followed by 40 μL/well of cAMP working detection solution (made as directed in the HitHunter® kit) and incubated at room temperature in the dark for 1 hour. Next, 40 μL of cAMP solution A (from the HitHunter® kit) was added. The assay plate was incubated for 3 additional hours at room temperature in the dark. The assay plate was read on a standard luminescence plate reader (EnVision, PerkinElmer) at 0.1 to 1 second/well. Data analysis was performed using statistical analysis software (GraphPad Prism, V6).

Results and Conclusion

The biological activity of the tested constructs is provided in Table 2 and in FIG. 16 (single experiments) and 17 (repeated experiments).

The average EC50s for both the recombinant human Relaxin-2 and fusion polypeptides from several assays has been summarized in Table 2.

TABLE 2 Biological activity of some Relaxin 2 fusion constructs Construct EC50 (M) rhRLX2 (R&D Systems, 1.06E−10* catalogue number 6586-RN-025) Fc_hRLX2_4-15AA 9.32E−10* Fc_hRLX2_15-15AA 9.84E−10* Fc-YTE-TM_hRLX2_15-15A 5.39E−09# Fc-YTE-FQQ_hRLX2_15-15A 4.56E−09# *Values are mean values from 5 independent repeats #Values are mean values from 3 independent repeats

These results show that the Relaxin 2 fusion polypeptides of the invention are biologically active, as seen using an in vitro cell-based assay.

Due to the variability of the in vitro cell based cAMP stimulation assay, recombinant human relaxin-2 is always used in each assay as a positive control. As a further comment, the activity ratio calculation is only meaningful for each assay where both the fusion peptide and recombinant human relaxin-2 were included. The activity of the fusion polypeptide (EC50) is compared to the activity of the recombinant human relaxin-2 (EC50) to derive the ratio, which is about 10 or about 50, when the average EC50 values obtained in several independent repeats are used to determine said ratio. In contrast, calculated on the basis of EC50 values obtained within the same assay (one repeat), the ratio is lower, typically comprised between about 10 and 20, or about 15 (see, for instance, FIG. 20 ).

Example 3: Specificity of Fc-Relaxin-2 Fusion Polypeptides for Relaxin-2 Receptor

The relaxin family peptides produce their physiological effects by activating a group of four G protein-coupled receptors (GPCRs), which can be stimulated (Gs) or inhibited (Gi) by their ligands. Relaxin 2 binds specifically to the receptor RXFP1.

To check the binding and activation specificity of Relaxin 2 fusion polypeptides for the RXFP1 receptor, the following cell lines were purchased from DiscoverX (Fermont, Calif.):

-   -   cAMP Hunter™ CHO-K1 RXFP2 Gs cell line (Catalogue number         95-0140C2, DiscoverX), ligand is INSL3 (Catalogue number         4544-NS, R&D System)     -   cAMP Hunter™ CHO-K1 RXFP3 Gi cell line (Catalogue number         95-0102C2, DiscoverX), ligand is Relaxin-3 (Catalogue number         TP723377, Origene)     -   cAMP Hunter™ CHO-K1 RXFP4 Gi cell line (Catalogue number         95-0134C2, DiscoverX), ligand is INSL5 (Catalogue number         TP723251, Origene)     -   cAMP Hunter™ CHO-K1 ADCYAP1R1 Gs/Gq cell line (Catalogue number         95-0064C2, DiscoverX), ligand is PACAP1-27 (Catalogue number         1183, R&D Systems).

RXFP2 cell lines naturally overexpress Gs wild-type GPCRs RXFP2 and are designed to detect the increase in intracellular cAMP levels in response to agonist stimulation. RXFP3 and RXFP4 cell lines naturally overexpress Gi wild-type GPCRs RXFP3 and RXFP4, respectively, and are designed to detect the decrease in intracellular cAMP levels in response to antagonist stimulation. CHO-K1 ADCYAP1R1 is an unrelated GPCR overexpression cell line and is used as assay control.

These cell lines were used to measure the activity of IgG1-Fc human relaxin fusion polypeptides with the HitHunter® cAMP XS+ chemiluminescent detection kit from DiscoverX (Catalogue number 90-0075, Fremont, Calif.). cAMP assays were carried out as described in Example 2, except for cell lines RXFP3 and RXFP4, in which 25 μM or 20 μM Forskolin (Catalogue number 1099, R&D Systems) respectively, was added to the dilution plate and serum-free medium to increase intracellular levels of cAMP as the ligands used in the assay will inhibit cAMP production. Experiments were performed at least twice.

Results and Conclusion

The results are shown in FIG. 22 . The Relaxin 2 fusion polypeptides tested have a minimal activity in the RXFP2 expression cell line, and are not active in the other related RXFP expression cell lines (RXFP3 and RXFP4). As expected, no activity was observed in the ADCYAP1R1 Gs/Gq cell line.

Example 4. Fc-Relaxin-2 Fusion Polypeptides Induce VEGF Expression in THP-1 Cells

The ability of the Relaxin 2 fusion polypeptides to induce the expression of VEGF, a known downstream target of Relaxin 2 (Xiao et al., 2013), was assayed. The expression of VEGF RNA in THP-1 cells (Catalogue number TIB-202, ATCC) was analyzed by quantitative real-time PCR. A total of 106 cells/ml was seeded in a 24-well flat bottom plate (Catalogue number 353226, Corning) in 400 μl test media (RPMI-1640 without phenol red, 0.5% FBS, 1% Pen/Strep and 0.05 mM of 2-mercaptoethanol). After 24 h incubation at 37° C., 5% CO₂, human relaxin-2 (Catalogue number 3956-RN, R&D Systems) or Fc-hRelaxin-2 fusion polypeptides, were added to the cells in the plate for 2.5 h at 37° C. RNA isolation and purification from THP-1 cells was performed using Qiagen's QiaShredder (Catalogue number 79656, Qiagen) and RNA Plus Mini Kit (Catalogue number 74134, Qiagen), following the manufacturer's protocol. The mRNA concentrations were measured by NanoDrop (Thermofisher) and samples were normalized to the same starting concentration (range between RT-PCR set up; 50-20 ng/μl). RT-PCR samples were prepared using Express One-Step Superscript qRT-PCR kit (Catalogue number 11791-200, Invitrogen) and primer/probe sets were as follows: VEGFA human (Hs00900055_m1, catalogue number 4331182, ThermoFisher Scientific) and GAPDH human (Hs02758991_g1, catalogue number 4331182, ThermoFisher Scientific). RT-PCR reactions were performed using 7900HT Fast Real-Time PCR machine with cycle set up of: 1 cycle of 50° C. for 15 min for cDNA synthesis, 1 cycle at 95° C. for 20 sec in Taq activation and 40 cycles at two temperatures of 95° C. for 1 sec and 60° C. for 20 sec for qPCR. The relative fold change in VEGF mRNA level was calculated by the comparative Ct method using GAPDH expression for normalization. Results were calculated as fold changes over no treatment control. Experiments were performed in triplicates with an n>2. Data was analyzed by paired two tailed t-test utilizing Prism GraphPad, V6.

Results and Conclusion

As shown in FIG. 23 (top), the Relaxin 2 fusion polypeptides tested significantly stimulate the VEGF transcripts in THP-1 cells as compared to a mock “no treatment” control at concentrations of 5 ng/ml, 50 ng and 80 ng/ml. Similarly, commercially available recombinant human relaxin 2 (R&D Systems) also significantly increased the VEGF transcripts in THP-1 cells as compared to “no treatment” control cells, at a concentration of 0.01, 0.06, and 10 ng/ml. In order to make a comparison with human relaxin 2, the Fc Relaxin 2 fusion polypeptide concentration was adjusted based on molecular weight difference (6×) and reduction of activity seen in the cAMP assay (10-15 fold).

FIG. 23 (bottom) shows that the Relaxin 2 fusion polypeptides tested significantly stimulate the VEGF transcripts in THP-1 cells as compared to a mock “no treatment” control.

Example 5: PK Profile of Some Fc-Relaxin 2 Fusion Polypeptides

The pharmacokinetic (PK) profiles of some Relaxin 2 fusion polypeptides of the invention were determined using a Relaxin ELISA assay. The rat in vivo PK profiles were determined for the following fusion polypeptides: Fc_hRLX2_4-15AA and Fc_hRLX2_15-15AA.

SureBlue™ TMB Substrate (KPL, 52-00-01. Ready-to-use SureBlue™ TMB Microwell Peroxidase Substrate) and TMB Stop Solution (KPL, 50-85-05) were used to develop the assays. Fc_hRLX2_4-15AA and Fc_hRLX2_15-15AA fusion polypeptides were administered to 8-week-old Wistar rats (Charles River) by the intravenous (IV) or subcutaneous (SC) route at 4 mg/kg. Blood samples were collected at 5 minutes, 30 minutes, 3 hours, 8 hours, 1 day, 2 days, 3 days, 4 days, 7 days, 9 days, 14 days and 21 days post drug administration for the IV route, and at 8 hours, 1 day, 2 days, 3 days, 4 days, 7 days, 9 days, 14 days and 21 days post drug administration for the SC route. Samples were collected into a tube containing EDTA and placed on ice immediately. Samples were centrifuged for 15 minutes at 1000×g within 30 minutes of collection. Aliquoted samples were stored at −20° C. and later tested by ELISA. The half-life was assessed using an Fc capture and Relaxin detection ELISA assay (using the polyclonal antibody from R&D Systems Relaxin detection ELISA kit, Catalogue number DRL200).

Results and Conclusion

FIG. 24 shows the in vivo PK profile of Fc_hRLX2_4-15AA following either subcutaneous (SC) or intravenous (IV) administration in rats. Following SC administration, the peak plasma concentration was achieved within 8 to 24 hours. The mean terminal half-life estimated from non-compartmental analysis was 2.46 days for the IV dose group and 3.21 days for the SC dose group.

FIG. 25 shows the in vivo PK profile of Fc_hRLX2_15-15AA following either SC or IV administration in rats. Following SC administration, the peak plasma concentration was achieved within 8 to 24 hr. The mean terminal half-life estimated from non-compartmental analysis was 3.59 days for the IV dose group and 3.75 days for the SC dose group.

In comparison, the half-life of human Relaxin 2 following IV administration is about 0.09+/−0.04 hours, i.e. 5.4+/−2.4 minutes in humans (Chen et al. 1993).

Example 6: PK Study in FcRn Transgenic Mouse

The extended half-life offered by the YTE mutations (M252Y/S254T/T256E) present in the Fc-fusion polypeptides is confirmed by a PK profile study carried out for the Fc-YTE-hRLX2-15-15AA, Fc-YTE-FQQ-hRLX2-15-15AA and Fc-YTE-TM-hRLX2-15-15AA fusion polypeptides administered either intravenously or subcutaneously, at a dose of 6 mg/kg, in an FcRn transgenic mouse generated in-house. The extended half-life was assessed using an Fc capture and Relaxin detection ELISA assay (using the polyclonal antibody from R&D Systems Relaxin detection ELISA kit, Catalogue number DRL200).

FIG. 26 shows the mouse in vivo PK profile of Fc_hRLX2_15-15AA following either SC or IV administration. The mean terminal half-life was approximately 26.5% greater in the SC dose group compared to the IV dose group.

FIG. 27 shows the mouse in vivo PK profile of Fc_hRLX2_15-15AA following SC administration at a dose of 1 mg/kg, 6 mg/kg or 30 mg/kg. Peak serum concentration was reached between 24-72 hours following SC administration. The mean terminal half-life ranged from 4.59 to 7.06 days. The dose-normalized Cmax decreased with an increase in dose.

Example 7: In Vitro Activity of Some Fc-Relaxin-2 Fusion Polypeptides in Human and Mouse Cell Lines and RXFP2 Selectivity (in Cell-Based cAMP Activity Assay)

Some of the Fc-Relaxin-2 fusion polypeptides of the invention (Fc_hRLX2_15-15AA, Fc-TMΔTHTΔK_hRLX2_21-15AA, Fc-TMΔTHTΔK_hRLX2(BA)_21-15AA, hRLX2-Fc-TMΔTHTΔK_15-24AA, hRLX2(BA)-Fc-TMΔTHTΔK_15-24AA) produced as described in Example 1 were tested for biological activity, e.g., stimulation of one or more cellular receptor responses, by the following methods.

Stable CHO cell lines expressing human or mouse RXFP1 receptor, or human RXFP2 were purchased from DiscoverX and used to test receptor specificity. The cell lines used were as follows: cAMP Hunter™ CHO-K1 RXFP1 Gs cell line (Catalogue number 95-0127C2, DiscoverX), cAMP Hunter™ CHO-K1 RXFP2 Gs cell line (Catalogue number 95-0140C2, DiscoverX), cAMP Hunter™ CHO-K1 mRXFP1 Gs cell line (Catalogue number 95-0180C2, DiscoverX). Activation of these receptors results in downstream production of cAMP second messenger that can be measured in a functional activity assay.

Routine cAMP assays were performed using bovine serum albumin (BSA)-based assay buffer: Hanks Balanced Salt Solution (Sigma #H8264) supplemented with 0.1% BSA (Sigma #A9418) and 0.5 mM IBMX (Sigma #17018), adjusted to pH 7.4 with 1 M NaOH. A frozen cryo-vial of cells expressing the receptor of interest was thawed rapidly in a water-bath, transferred to pre-warmed cell media and spun at 240×g for 5 minutes. Cells were re-suspended in cell media at an optimized concentration (e.g., hRXFP1 at 3.33×10⁴ cells/ml).

30 μL cell suspension was added to Poly-D-Lysine-coated 384-well plates (Greiner #781946) and allowed to adhere overnight. The next day the media was flicked out of the plates and replaced with 5 μL assay buffer. Eleven-point serial dilutions of test recombinant peptide/Fc fusion samples were added to the cells using a non-contact liquid dispenser (ECHO™, Labcyte). All sample dilutions were made in duplicate. An additional 5 μL assay buffer was added to each well and the plates incubated at room temperature for 30 minutes.

cAMP levels were measured using a commercially available cAMP dynamic 2 HTRF kit (Cisbio, Cat #62AM4PEJ), following the two-step protocol as per manufacturer's recommendations. In brief; anti-cAMP cryptate (donor fluorophore) and cAMP-d2 (acceptor fluorophore) were made up separately by diluting each 1/20 in conjugate & lysis buffer provided in the kit. 5 μL anti-cAMP cryptate was added to all wells of the assay plate, and 5 μL cAMP-d2 added to all wells except non-specific binding (NSB) wells, to which conjugate and lysis buffer was added. Plates were incubated at room temperature for one hour and then read on an Envision (Perkin Elmer) using excitation wavelength of 320 nm and emission wavelengths of 620 nm & 665 nm. Data was transformed to % Delta F as described in manufacturer's guidelines and then transformed to percent activation of maximal native agonist response and analysed by 4-parameter logistic fit to determine EC₅₀ values.

The results are compared to corresponding results for recombinant human Relaxin-2 (Catalogue number 6586-RN, R&D Systems) in the case of hRXFP1 cells, mRelaxin-1 (Catalogue number 6637-RN, R&D Systems) in mRXFP1 cells or INSL-3 (Catalogue number 4544-NS, R&D Systems) in hRXFP2 cells. We used unconstrained 4 parameter logistic fit of data, curve mid-point to determine EC₅₀.

Results and Conclusion

The biological activity of the tested fusion polypeptides is provided in Table 3 and the results of one representative assay for each polypeptide are presented in FIG. 28 . Due to the variability of the in vitro cell based cAMP stimulation assay, recombinant human Relaxin-2 is always used in each assay as a positive control.

The average EC50s for both the recombinant human Relaxin-2 and fusion polypeptides from several assays has been summarized in Table 3.

TABLE 3 Biological activity of some Relaxin-2 fusion constructs hRXFP1 hRXFP2 mRXFP1 Construct EC50 (M) EC50 (M) EC50 (M) rhRLX2 1.38E−10***  1.46E−07* 6.68E−11*** Fc_hRLX2_15-15AA 1.84E−09** >9.32E−06* 1.51E−09** Fc-TMΔTHTΔK_hRLX2_21-15AA 2.60E−09* >6.78E−06* 2.52E−09* Fc-TMΔTHTΔK_hRLX2(BA)_21-15AA 1.56E−08** >8.22E−06** 8.82E−09** hRLX2-Fc-TMΔTHTΔK_15-24AA 4.97E−09* >3.09E−07* 2.23E−09* hRLX2(BA)-Fc-TMΔTHTΔK_15-24AA 1.13E−09* >4.33E−06* 8.78E−10* *Values are mean values from 1 independent repeat **Values are mean values from 2 independent repeats ***Values are mean values from 3 independent repeats

These results show that:

-   -   The Relaxin-2 fusion polypeptides tested, comprising either the         Fc moiety attached at the N-terminus of the Relaxin fusion         polypeptide or at the C-terminus of the Relaxin fusion         polypeptide, are biologically active.     -   The Relaxin-2 fusion polypeptides tested, comprising either         chains orientations (B-A or A-B), are biologically active.     -   Selectivity between RXFP1 and RXFP2 is retained for all         Fc-Relaxin-2 fusion polypeptides tested.

The results also show that the Relaxin-2 fusion polypeptides tested have similar species cross-reactivity between human and mouse than human Relaxin-2. In particular, they show that fusion to a Fc domain does not affect species cross-reactivity of human Relaxin-2.

Example 8: Fc_hRLX2_15-15AA Prevents Isoproterenol-Induced Cardiac Hypertrophy in Mice

A total of 6 study groups with n=8 mice (C57BL/6J male mice) per group were performed. The groups were: vehicle, Fc_hRLX2_15-15AA, isoproterenol, isoproterenol+enalapril, isoproterenol+recombinant human relaxin 2, and isoproterenol+Fc_hRLX2_15-15AA. Drugs and vehicle were delivered by Alzet minipumps (model 1002; rate: 0.25 μl/hr (±0.05), 6 μl one day @37° C.) or subcutaneous injection for Fc_hRLX2_15-15AA.

Isoproterenol was made as follows: A 500 mM solution (123.9 mg/ml) freshly in 0.0002% Na-Asc saline, 0.22 μM filtered). The final [Iso] concentration in minipump: 15 mg/kg/day=15 mg/247.72/6 μl/1000 g=10.1 mM per gram of body weight (BVV). Vehicle was 0.0002% Na-ascorbate, Sigma catalog #A7631.

Enalapril was made as follows: Enalapril is used as maleate salt, MW of 492.52, Sigma catalog #E6888. A 200 mM stock solution (98.5 mg/ml) freshly in methanol, 0.22 μM filtered. The final concentration in minipump: 2.5 mg/kg/day=2.5 mg/492.52/6 μl/1000 g=0.846 mM per gram of body weight (BVV), i.e., one minipump for 30 gram of mouse will need 19.0 μl of 200 mM Ena (150 μl×0.846/200 mM×30 g BW).

Isoproterenol+Enalapril: Isoproterenol and enalapril made as described above were included in the pump.

The six groups and dosing are given in Table 4.

TABLE 4 Group Test Substance Dose 1 Vehicle — 2 Fc_hRLX2_15-15AA 30 mg/kg (SC, day 0 and day 7) + minipump for vehicle 3 Isoproterenol (ISO) 15 mg/kg/day 4 ISO + Enalapril 15 mg/kg/day + 2.5 mg/kg/day 5 ISO + rhRLX2 15 mg/kg/day + 500 ug/kg/day 6 ISO + Fc_hRLX2_15- 15 mg/kg/day + 30 mg/kg 15AA (SC, day 0 and day 7)

At the end of the study, body weight, heart weight, lung weight, and tibia length were measured. Additionally, histology and collagen assays were performed using the heart samples.

Fibrosis was measured based on the detection of hydroxyproline (Total collagen assay, QuickZyme Biosciences). Histology (H & E and Masson Trichrome) was also carried out on formalin treated heart tissue following 2 weeks of treatments.

Results and Conclusion

FIG. 29A shows the heart weight (HVV) to tibia length (TL) ratio and FIG. 29B shows collagen content.

Treatment with isoproterenol resulted in a significant increase in cardiac hypertrophy and fibrosis compared to vehicle or Fc_hRLX2_15-15AA alone, as indicated by the increase in HW/TL and collagen content (FIG. 29 A, B).

The increase in cardiac hypertrophy and fibrosis observed with isoproterenol was significantly attenuated when isoproterenol was administered concomitantly with enalapril, rhRLX2 or Fc_hRLX2_15-15AA (FIGS. 29 A, B).

The data from the histology study were consistent with the collagen and hypertrophy measurements (data not shown).

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The invention claimed is:
 1. A nucleic acid molecule encoding a fusion polypeptide comprising a half-life extending moiety fused to A-L-B or B-L-A, wherein: A is a Relaxin A chain polypeptide or a variant thereof; B is a Relaxin B chain polypeptide or a variant thereof; and L is a linker polypeptide comprising at least 15 amino acids, wherein the fusion polypeptide has Relaxin activity.
 2. The nucleic acid molecule of claim 1, wherein the Relaxin A chain is a Relaxin 2 A chain and the Relaxin B chain is a Relaxin 2 B chain.
 3. The nucleic acid molecule of claim 1, wherein the linker polypeptide L is 15 to 20 amino acids in length.
 4. The nucleic acid molecule of claim 1, wherein the linker polypeptide L comprises three or more repeats of the sequence GGGGS (SEQ ID NO. 58).
 5. The nucleic acid molecule of claim 1, wherein the linker polypeptide L comprises the sequence GGGGSGGGGSGGGGS (SEQ ID NO. 57).
 6. The nucleic acid molecule of claim 1, wherein the linker polypeptide L consists of the sequence GGGGSGGGGSGGGGS (SEQ ID NO. 57).
 7. The nucleic acid molecule of claim 1, wherein the half-life extending moiety is an immunoglobulin Fc region.
 8. The nucleic acid molecule of claim 7, wherein the Fc region is derived from a human IgG1 immunoglobulin.
 9. The nucleic acid molecule of claim 7, wherein the Fc region has an amino acid sequence comprising at least one of the following combinations of amino acid modifications: (i) Fc-YTE (M252Y, S254T, T256E); (ii) Fc-FQQ (L234F, L235Q, K322Q); (iii) Fc-TM (L234F, L235E, P331S); (iv) Fc-YTE-FQQ (M252Y, S254T, T256E, L234F, L235Q, K322Q); (v) Fc-YTE-TM (M252Y, S254T, T256E, L234F, L235E, P331S); (vi) Fc-TM-ΔTHT (L234F, L235E, P331S, D221G, K222G, T223G, H224S, T225A); (vii) Fc-TM-ΔTHTAK (L234F, L235E, P331S, D221G, K222G, T223G, H224S, T225A, ΔK447); wherein the amino acid numbering is according to the EU index as in Kabat.
 10. The nucleic acid molecule of claim 1, wherein the half-life extending moiety is at the N-terminus of the fusion polypeptide.
 11. The nucleic acid molecule of claim 1, wherein the half-life extending moiety is fused via a connector polypeptide.
 12. The nucleic acid molecule of claim 11, wherein the connector polypeptide comprises the amino acid sequence GGSP (SEQ ID NO. 56) or GGGGSGGGGSGGGGS (SEQ ID NO. 57).
 13. The nucleic acid molecule of claim 11, wherein the connector polypeptide comprises the amino acid sequence GGGGSGGGGSGGGGSGGGGGS (SEQ ID NO. 69) or AAAGGGGSGGGGSGGGGSGGGGSA (SEQ ID NO. 70).
 14. A vector comprising the nucleic acid molecule of claim
 1. 15. A host cell comprising the vector of claim
 14. 16. A method of producing a fusion polypeptide comprising culturing the host cell of claim 15 and collecting the fusion polypeptide.
 17. A nucleic acid molecule encoding a fusion polypeptide having Relaxin activity, wherein the fusion polypeptide has the sequence as set forth in any one of SEQ ID NOs: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, and
 28. 18. A vector comprising the nucleic acid molecule of claim
 17. 19. A host cell comprising the vector of claim
 18. 20. A method of producing a fusion polypeptide comprising culturing the host cell of claim 19 and collecting the fusion polypeptide. 